Ink jet printers are well known in the art. Generally, an ink jet printer includes an array of nozzles or orifices, a supply of ink, a plurality of ejection elements (typically either expanding vapor bubble elements or piezoelectric transducer elements) corresponding to the array of nozzles and suitable driver and control electronics for controlling the ejection elements. Typically, the array of nozzles and the ejection elements along with their associated components are referred to as a print head. It is the activation of the ejection elements which causes drops of ink to be expelled from the nozzles. The ink ejected in this manner forms drops which travel along a flight path until they reach a print medium such as a sheet of paper, overhead transparency, envelope or the like. Once they reach the print medium, the drops dry and collectively form a print image. Typically, the ejection elements are selectively activated or energized as relative movement is provided between the print head and the print medium so that a predetermined or desired print image is achieved.
Generally, the array of nozzles, supply of ink, plurality of ejection elements and driver electronics are packaged into an ink jet cartridge. In turn, the printer includes a carriage assembly for detachably mounting the ink jet cartridge thereto. In this manner, a fresh ink jet cartridge may be installed when the ink supply of the current ink cartridge has been consumed. Recently, the postage meter industry and other envelope printing industries have begun to incorporate ink jet printers having user replaceable ink jet cartridges.
A typical postage meter (one example of a postage printing apparatus) applies evidence of postage, commonly referred to as a postal indicia, to an envelope or other mailpiece and accounts for the value of the postage dispensed. As is well known, postage meters include an ascending register that stores a running total of all postage dispensed by the meter and a descending register that holds the remaining amount of postage credited to the meter and that is reduced by the amount of postage dispensed during a transaction. Because U.S. Postal Service regulations require that postage be paid in advance, it had traditionally been required that the user of a postage meter periodically present the meter to a Postal Service employee for recharging. However, more recently it is possible to recharge a meter remotely using telephone communications. At the time of recharging, the user pays to the Postal Service the amount of postage to be credited to the meter and the meter is recharged by increasing the setting of the descending register by the amount paid. The postage meter generally also includes a control sum register, which provides a check upon the descending and ascending registers. The control sum register has a running account of the total funds being added into the meter. The control sum register must always correspond with the summed readings of the ascending and descending registers. The control sum register is the total amount of postage ever put into the machine and it is alterable only when adding funds to the meter. In this manner, the dispensing of postal funds may be accurately tracked and recorded.
Generally, the postage meter may be incorporated into a mailing machine, which is also well known in the art, for automated handling of the mailpieces. Mailing machines are readily available from manufacturers such as Pitney Bowes Inc. of Stamford, Conn., USA and often include a variety of different modules, which automate the processes of producing mailpieces. The typical mailing machine includes a variety of different modules or sub-systems where each module performs a different task on a mailpiece, such as: singulating (separating the mailpieces one at a time from a stack of mailpieces), weighing, sealing (wetting and closing the glued flap of an envelope), applying evidence of postage, accounting for postage used (performed by the postage meter), feeding roll tape or cut tape strips for printing and stacking finished mailpieces. However, the exact configuration of each mailing machine is particular to the needs of the user. Customarily, the mailing machine also includes a transport apparatus, which feeds the mailpieces in a path of travel through the successive modules of the mailing machine.
To achieve increased throughput, it is generally advantageous to print the postal indicia in one pass. In this way, the envelopes can be fed in a continuous fashion past a printer module containing the ink jet printer without stopping or repositioning of the ink jet printer. Unfortunately, the current state of ink jet printing technology only provides for an ink jet print head having an array of nozzles with a small dimension (generally less than 0.50 inches). Thus, a single ink jet cartridge like those commonly available will not be able to print the entire postal indicia in one pass.
One way to attempt to resolve this problem is to cluster multiple ink jet cartridges together so as to extend the effective length of the linear array of nozzles. However, this increases the overall complexity of the system since the firing of the nozzles between the ink jet cartridges must be coordinated so that a quality printed image is produced. This problem is exacerbated by manufacturing tolerances associated with aligning the ink jet cartridges to each other and coordinating the print data signals with the feeding of the mailpiece.
Therefore, there is a need for a mailing machine including a control system and an ink jet printer having a pair of ink jet cartridges that are capable of printing a postal indicia is one pass. More particularly, there is a need for a mailing machine wherein the control system ensures that the print data signals sent to the pair of ink jet cartridges, respectively, are coordinated so as to produce a quality printed postal indicia.